NSW1 experienced sustained negative pricing on 18 August 2026, with two consecutive intervals settling at negative RRP (minimum -$1.38/MWh) during early morning hours. This followed a sharp price collapse from the $40–46 range into negative territory within a single 5-minute interval.
The negative pricing occurred during a period of high renewable generation, with solar output at 2,437.89 MW and wind at 553.1 MW meeting relatively low overnight demand, whilst coal generation remained firm at 4,463.79 MW. A binding constraint with marginal values between $3.46 and $5.07/MWh was active across the event window, indicating that dispatch flexibility was constrained; the inability to reduce coal output or export excess supply suggests the constraint prevented efficient load-matching, forcing the region into an oversupply condition that pushed prices negative.
Causal analysis generated by gridIQ's synthesis model from live AEMO market data: dispatch prices, generation mix, interconnector flows and market notices in the interval surrounding the event.